The research is designed to examine quantitatively the ways in which unsaturated fatty acids exert beneficial effects in supporting normal cell physiology. Three mechanisms for these effects are generally regarded: Non-selective contributions to membrane fluidity or plasticity; selective interactions of acyl chains with cellular proteins or enzymes; formation of regulatory autacoids (e.g., prostaglandins). We will use mutants of E. coli and S. cerevisiae for which no lipoidal autacoids are known, in order to minimize the likelihood of the latter interpretation. Cellular responses to a given acyl chain will be classified in terms of whether they appear due to additive, non-specific, chain-chain interactions generally associated with fluidity or whether they seem due to specific interactions of lipid and protein. The responses studied include cell replication and growth, induction and derepession of enzymes, regulation of respiration and mitochondriogenesis, and cell-cell interactions. We hope to assign the limits to which structural differences in acyl chains can influence these processes, and to designate the degree to which cell metabolic regulatory systems can modulate the specific and non-specific effects. These modulations in eukaryotic cells will also be correlated with the occurrence of phospholipidosis and/or triglyceridosis and with the changes in synthetic enzyme activities that cause some unsaturated acids to be less effective than others. The results will be applied to more complex mammalian cell systems to help interpret the possible impact of various dietary lipids upon human physiology. BIBLIOGRAPHIC REFERENCES: Positional Specificity of Cyclopropane Ring Formation from Cis-Octadecenoic Acid Isomers in Escherichia coli (1976) Ohlrogge, J. B., Gunstone, F.D., Ismail, I.A., and Lands, W. E. M., Biochim. Biophys. Acta 431, 257-267. Quantitative Effects of Unsaturated Fatty Acids in Microbial Mutants. VII. Influence of the Acetylenic Bond Location on the Effectiveness of Acyl Chains (1977) Lands, W. E. M., Ohlrogge, J. B., Robinson, J. R., Sacks, R. W., Barve, J. A., and Gunstone, F. D., Biochim. Biophys. Act 486, 451-461.